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Full text of "Circuits"

Miniature Beeping Circuit Prank 



Make] Projects 



Miniature Beeping Circuit Prank 



Written By: Jason Poel Smith 



TOOLS: 

Dremel tool (optional) (1) 
Soldering iron (1) 


PARTS: 

Printed Circuit Board (RadioShack #276- 

159) (1) 

555 Timer IC (RadioShack #276-1723) 

in 

• 3- 16V Piezo Buzzer (RadioShack #273- 
074) (1) 

100 F Capacitor (10V or higher) (1) 
1kQ Resistor (1) 
4.7MQ Resistor (1) 
Button cell Batteries (3) 
/ used LR932 cells but other sizes will 
work 

Jumper Wire Pack (1) 
Larae Paperclip (1) 



SUMMARY 

Here is a video of the build. 



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Miniature Beeping Circuit Prank 



Step 1 — Circuit Design 





4,5 V 






4.7MQ < 












< 


Piezo 
Buzzer 


lkQ < 




7 8 4 

3 

555 
6 

2 

1 


J 


100uF = 































• The circuit is a basic 555 timer 
circuit in astable mode. In this 
configuration the IC sends a brief 
pulse to the buzzer every few 
minutes. The values of the 
resistors and the capacitor 
determine how often the buzzer will 
sound and how long each pulse will 
be. With the values that I used, it 
beeps about every 6-7 minutes. (If 
the capacitor is completely 
discharged, the first beep may take 
up to twice as long.) 

• Increasing the value of either the 
capacitor or the resistor between 
pins 7 and 8 will increase the 
amount of time between beeps. 
Increasing the value of the resistor 
between pins 6 and 7 will increase 
the length of each beep. 
Decreasing these values will have 
the opposite effect. 



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Miniature Beeping Circuit Prank 
Step 2 — Make the battery connectors. 




• The only parts that you need to 
make are the battery connector 
pins. To make these, cut off two 
pieces of the paper clip that are 
about an inch long and fold each of 
them in half. The bent end is where 
they will contact with the battery. 
The cut ends will be soldered to the 
board. 



Step 3 — Solder the circuit to the board 




• Then solder all the components 
onto the board. If you are using the 
same PCB, you can just copy my 
layout. If not, just make sure to 
follow the schematic on Step 1 and 
check all the pin connections. 
When soldering the battery 
connector pins, try to align them so 
that they are leaning slightly 
towards each other. This will help 
make a tight connection with the 
batteries. 



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Miniature Beeping Circuit Prank 



Step 4 — Trim the Circuit Board 




After soldering everything together, I trimmed off the unused part off the circuit board to 
make it easier to hide. I used wire cutters to remove the large chunks and a Dremel to trim 
up to the edge of the circuit board. In hindsight, it would probably be a lot easier to cut the 
board to the needed dimensions before soldering all the parts onto the board. So if you 
know where all your parts will be, I recommend trying that. 



Step 5 — Finished Circuit 




• Then just insert the batteries and your annoying beeping prank is ready. Now all you have 
to do is find a good hiding spot. You can put it inside someone's computer, tape it to the 
inside of a drawer, or stick it behind a piece of furniture. Use your imagination. The 
batteries should last from several hours to several days depending on the size of the 
battery that you used. But your victim will probably find it before the battery dies depending 
on how determined/obsessive they are. Be creative and have fun. 

last generated on 2012-10-31 11:33:36 PM. 



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Page 4 of 4